H a n d s o n, p r o j e c t b a s e d

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Chapter 18
try it yourSelf
18-2. Short Entries:
The __str__() method in the Entry model currently appends 
an ellipsis to every instance of Entry when Django shows it in the admin site 
or the shell. Add an if statement to the __str__() method that adds an ellipsis 
only if the entry is longer than 50 characters. Use the admin site to add an 
entry that’s fewer than 50 characters in length, and check that it doesn’t have 
an ellipsis when viewed.
18-3. The Django API:
When you write code to access the data in your project, 
you’re writing a query. Skim through the documentation for querying your data 
at https://docs.djangoproject.com/en/2.2/topics/db/queries/. Much of what 
you see will look new to you, but it will be very useful as you start to work on 
your own projects.
18-4. Pizzeria:
Start a new project called pizzeria with an app called pizzas. 
Define a model Pizza with a field called name, which will hold name values, 
such as Hawaiian and Meat Lovers. Define a model called Topping with fields 
called pizza and name. The pizza field should be a foreign key to Pizza, and 
name
should be able to hold values such as pineapple, Canadian bacon, and 
sausage
.
Register both models with the admin site, and use the site to enter some 
pizza names and toppings. Use the shell to explore the data you entered.
Making Pages: The Learning Log Home Page
Making web pages with Django consists of three stages: defining URLs, 
writing views, and writing templates. You can do these in any order, but in 
this project we’ll always start by defining the URL pattern. A URL pattern 
describes the way the URL is laid out. It also tells Django what to look for 
when matching a browser request with a site URL so it knows which page to 
return.
Each URL then maps to a particular view—the view function retrieves 
and processes the data needed for that page. The view function often ren-
ders the page using a template, which contains the overall structure of the 
page. To see how this works, let’s make the home page for Learning Log. 
We’ll define the URL for the home page, write its view function, and create 
a simple template.
Because all we’re doing is making sure Learning Log works as it’s sup-
posed to, we’ll make a simple page for now. A functioning web app is fun 
to style when it’s complete; an app that looks good but doesn’t work well 
is pointless. For now, the home page will display only a title and a brief 
description.

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Getting Started with Django